use automake and libtool

This commits replaces the handwritten makefile with automake+libtool.
There is some hackery needed for the LD_PRELOAD shared library,
but apart from that there is nothing special and it is a large gain in
portability and standardization.

The spec file is modified as little as is needed to properly build
the RPMs.

m4/.gitignore

@@ -0,0 +1,5 @@
+/libtool.m4
+/lt~obsolete.m4
+/ltoptions.m4
+/ltsugar.m4
+/ltversion.m4